Traditionally, digitally-controlled ink jet color printing is accomplished by one of two technologies. The first technology is commonly referred to as “drop on demand” (DOD) ink jet printing. The second technology is commonly referred to as “continuous stream” or “continuous” ink jet printing.
Continuous printing devices that deflect drops using a gas flow are known. U.S. Pat. No. 4,068,241 to Yamada, issued Jan. 10, 1978, entitled “Ink-jet recording device with alternate small and large drops,” describes a printing device that uses a gas flow perpendicular to the drop trajectory to separate large drops and small drops formed by a printhead. The small drops are deflected more by the gas flow than the large drops. The large drops are collected by a catcher while the small drops were deflected past the catcher and allowed to strike a recording medium.
However, in continuous printing devices that use a gas flow, for example, an air flow, to deflect drops formed from an array of nozzles (commonly referred to as jets), several factors can combine to produce less deflection of the drops formed from nozzles located at the end(s) of the nozzle array. These factors include an overall reduction in air velocity near the ends of a rectangular shaped duct that delivers the air flow to the drops; how far the duct extends beyond the nozzle array (the width of the duct beyond the extent of the jets); and resistance of the drops formed from the nozzles of the array (commonly referred to as the jet curtain) to the air flow that effects air flow around the end(s) of the nozzle array. Less deflection of drops formed from the nozzles located at the end(s) of the nozzle array adversely affects drop placement of these drops on a print media (commonly referred to as a “bow effect”).
As such, there is a need for an improved gas flow drop deflection device, a printhead including the same, and a method of printing including the same.